I personally think this is either part of an angle that TNA will bring up on the next iMPACT- something along the lines of AJ Styles no longer being Mr TNA (I think another poster mentioned this earlier, I forget who) or Styles is doing this to encourage TNA to look into his contract, and create a bit of a buzz to force TNA's hand.
AJ is a very loyal guy, we all know that. At any time in the past decade he could have jumped to WWE, and they WOULD sign him...they'd be crazy not to. But. he has always chosen to remain loyal to TNA, which is rare in wrestling. Styles has the ability to be a major star in WWE, the matches he could have with the likes of Punk, Bryan, Ziggler, Jericho etc would be fantastic and he would make alot more money there, but he has always seemed happy where he was.
Maybe he is thinking that at 36, the time is now to make the jump? If he waits much longer WWE are unlikely to want to invest alot of time and money in a guy who's selling point is his high-flying offense, which is obviously going to reduce as AJ gets older. If I was AJ I would seriously be giving consideration to jumping to WWE, and making the money now while I still can. TNA is still a minor company compared to WWE, and would be more than happy to take Styles back after a WWE run, as the "returning golden boy" no matter his age- we've all seen the veterans they are happy to bring in.
It would be a disgrace is WWE made him go to developmental though. We have all seen the great matches AJ has had with WWE trained wrestlers like Jeff Hardy, Kurt Angle, Christian etc, I fail to see the need for his to go to NXT. It's not like he is a guy who has spent all his career on the indies beating himself up, he knows how to wrestle WWE guys already.
There is also the issue of his name- he has AJ in big letters tattooed on his side, and unfortunately WWE already have AJ Lee on the roster, who is usually just referred to as AJ...I would hope that Styles is too big of a name for WWE to mess around with his ring name, but as they changed Mistico to Sin Cara (who was a huge name in Mexico), I'd expect they'd give Styles a shocking NXT style name like "Alexander Jones" or "Arthur James", or a name totally unrelated to the letters AJ and make him cover his torso.
Ultimately, if this is real and AJ Styles is seriously considering his options, then he needs to realise if he is ever going to go to WWE for a run (he isn't a big enough name to go in for a 1 off match later in his career like Sting or a returning Batista or Goldberg), he has to make the jump very soon while there is still going to be interest. It just depends on whether he wants the extra money and to wrestle infront of bigger crowds, or whether he is happy enough with his good TNA deal and is content to remain there.
Big choice to make AJ!